1. Field of the Invention
The present invention relates generally to tools and devices for cleaning and maintaining equipment and particularly to a chemical pigging apparatus for pipelines, more particularly for gas and oil pipelines.
2. Description of the Related Art
Practically all fluids, e.g., gas and oil, include various contaminants and materials that eventually fall out of solution or react with other materials. This is a particular problem in oil and gas pipelines and related conduits, as the contaminants and solids primarily include paraffins and asphalts that tend to build up along the inner walls of the pipes. If this condition is left to continue for a sufficiently long time, the buildup of contaminants can reach such a thickness that the inner diameter of the pipe becomes significantly restricted, thus reducing fluid flow and efficiency accordingly. Moreover, such buildups almost always result in uneven buildup within the pipes, thus creating turbulence and hydrodynamic or aerodynamic drag or resistance to the flow through the pipes.
Accordingly, various means have been developed in the past for cleaning such residue and deposits from the interior wall surfaces of pipes. Many, if not most, of these systems include remotely controlled or automated “pigs,” i.e., devices that conform to the interior of the pipe and travel through the pipe to accomplish their intended purpose automatically. These pipeline pigs that are adapted or configured for cleaning out the pipes generally use some form of physical action to remove the buildup within the pipes, such as mechanical scrapers or high pressure blasting with liquids and/or particulates. Those devices that use chemicals generally require some form of relatively complex system to dispense or release the chemicals from the pig.
An example of a pipeline cleanout pig is found in German Patent Publication No. 198 55 175 published on Jun. 15, 2000 to Fraunhofer Ges Forschung. This reference describes a pipeline pig having a pair of articulating arms extending from the flat front face thereof, with a third arm including a water discharge nozzle. The two arms articulate to guide and aim the nozzle as required to blast residue hydraulically from the internal pipe wall.
Thus, a chemical pigging apparatus for pipelines addressing the aforementioned problems is desired.